1. Field of the Invention
The present invention relates to a mechanism for automatically attaching and detaching structures to and from each other, in which a cam mechanism is used so that a pair of structures can be automatically attached and detached with a low insertion force.
2. Background
Heretofore, an electric connector assembly in which a cam mechanism is used for fitting a pair of connectors to each other by a low insertion force has been proposed in Japanese Patent Application No. JP-A-7-169529.
In FIG. 9 of the subject application, the electric connector assembly 60 is constituted by a first connector 61, a second connector 62, and an operation lever 63. Upon rotation of the operation lever 63, the first and second connectors 61 and 62 are attached to and detached from each other through the cam mechanism.
The first connector 61 includes a receiving portion 64 for receiving the second connector 62. Also, in the first connector 61, a through-hole 65 is formed in its upper wall so as to pierce the upper wall, a pair of support walls 66 extend upwardly from the upper wall at the opposite ends of the through-hole 64 so that the operation lever 63 is pivotally supported between the pair of support walls 66, and a pair of holding arms 67 and another pair of holding arms 68 extend upwardly from the upper wall at the front and rear sides of the support walls 66. In the top end portions of the respective pairs of the holding arms 67 and 68, hooks 67a and 68a are provided to hold the operation lever 63, respectively.
The second connector 62 includes a following arm 69 protruding from an upper wall surface of the second connector 62, and a circumferential groove 70 formed in a top end portion of the following arm 69.
The operation lever 63 has a cam groove 71 formed in its front end portion so that the operation lever 63 can pivot between the two pairs of holding arms 67 and 68.
In the condition in which the top end portion of the following arm 69 passes through the through-hole 65 of the first connector 61 and in which the operation lever 63 is locked by the hooks 67a of one pair of holding arms 67, the circumferential groove 70 of the following arm 69 and the cam groove 71 of the operation lever 63 are engaged with each other.
After the operation lever 63 is released from the locked state by means of the hooks 67a of the one pair of holding arms 67, the following arm 69 is lifted up toward the first connector 61 as the operation lever 63 pivots toward the other pair of holding arms 68. When the operation lever 63 is locked by the hooks 68a of the other pair of holding arms 68, the second connector 62 is entirely received in the receiving portion 64 of the first connector 61 and fitted to the first connector 61. In this manner, a terminal (not shown) in the first connector 61 and a terminal (not shown) in the second connector 62 are electrically connected to each other. Conversely, for detachment of the first and second connectors 61 and 62 from each other, the aforementioned procedure is reversed.
If an external force is exerted on the operation lever 63, however, there is a risk of breaking the support walls 66 and the pair of holding arms 67 (68) because the hooks 67a (68a) for locking the operation lever 63 in the first connector 61 are provided on the holding arms 67 (68) independent of the support walls 66 pivotally supporting the operation lever 63. Furthermore, there arises a problem that the number of constituent parts increases to bring an attendant increase in the cost of the mechanism because the operation lever 63 is pivotally supported on the support walls by means of a pin 72 which is made to pass through the operation lever 63 and the support walls 66.